The present invention relates to magnetoresistive transducers. More particularly, it relates to detector circuits utilizing the unique characteristics of magnetoresistive transducers.
Magnetoresistive transducers are elements formed of a magnetic material such as that known in the art as Permalloy, which exhibits a change in its electrical resistance as a function of an applied magnetic field. An additional feature of such magnetoresistive materials is that they are directionally sensitive relative to the direction of the field. That is, if the magnetic field lies parallel to the longitudinal dimension of the magnetoresistive elements, the resistive change response characteristic is significantly less than if the magnetic field lies transverse of the longitudinal dimension of the magnetoresistive elements, assuming the longitudinal polarization of the element. These characteristics of the magnetoresistive elements have enabled their use, heretofore, in circuits including bridge circuits for detecting ambient magnetic fields or, when the elements are placed adjacent to a current carrying conductor, have been used to detect the flow of current through that conductor. In this latter connection, such magnetoresistive elements have frequently been used in what has been defined as DC transformers. In such applications, the magnetoresistive transducers are operated in such manner as to provide an output signal which is a function of the magnitude of the applied magnetic field. Also because of the characteristics of the magnetoresistive elements, they have found their primary utility in responding to uni-directional or DC type fields.